Benchmark Evaluation of HOG Descriptors as Features for Classification of Traffic Signs

The purpose of this paper is to analyze the performance of the Histograms of Oriented Gradients (HOG) as descriptors for traffic signs recognition. The test dataset consists of speed limit traffic signs because of their high inter-class similarities.   HOG features of speed limit signs, which were extracted from different traffic scenes, were computed and a Gentle AdaBoost classifier was invoked to evaluate the different features. The performance of HOG was tested with a dataset consisting of 1727 Swedish speed signs images. Different numbers of HOG features per descriptor, ranging from 36 features up 396 features, were computed for each traffic sign in the benchmark testing. The results show that HOG features perform high classification rate as the Gentle AdaBoost classification rate was 99.42%, and they are suitable to real time traffic sign recognition. However, it is found that changing the number of orientation bins has insignificant effect on the classification rate. In addition to this, HOG descriptors are not robust with respect to sign orientation.

Traffic and Road Sign Recognition

This thesis presents a system to recognise and classify road and traffic signs for the purpose of developing an inventory of them which could assist the highway engineers’ tasks of updating and maintaining them. It uses images taken by a camera from a moving vehicle. The system is based on three major stages: colour segmentation, recognition, and classification. Four colour segmentation algorithms are developed and tested. They are a shadow and highlight invariant, a dynamic threshold, a modification of de la Escalera’s algorithm and a Fuzzy colour segmentation algorithm. All algorithms are tested using hundreds of images and the shadow-highlight invariant algorithm is eventually chosen as the best performer. This is because it is immune to shadows and highlights. It is also robust as it was tested in different lighting conditions, weather conditions, and times of the day. Approximately 97% successful segmentation rate was achieved using this algorithm.Recognition of traffic signs is carried out using a fuzzy shape recogniser. Based on four shape measures - the rectangularity, triangularity, ellipticity, and octagonality, fuzzy rules were developed to determine the shape of the sign. Among these shape measures octangonality has been introduced in this research. The final decision of the recogniser is based on the combination of both the colour and shape of the sign. The recogniser was tested in a variety of testing conditions giving an overall performance of approximately 88%.Classification was undertaken using a Support Vector Machine (SVM) classifier. The classification is carried out in two stages: rim’s shape classification followed by the classification of interior of the sign. The classifier was trained and tested using binary images in addition to five different types of moments which are Geometric moments, Zernike moments, Legendre moments, Orthogonal Fourier-Mellin Moments, and Binary Haar features. The performance of the SVM was tested using different features, kernels, SVM types, SVM parameters, and moment’s orders. The average classification rate achieved is about 97%. Binary images show the best testing results followed by Legendre moments. Linear kernel gives the best testing results followed by RBF. C-SVM shows very good performance, but ?-SVM gives better results in some case.

Color detection and segmentation for road and traffic signs

This paper aims to present three new methods for color detection and segmentation of road signs. The images are taken by a digital camera mounted in a car. The RGB images are converted into IHLS color space, and new methods are applied to extract the colors of the road signs under consideration. The methods are tested on hundreds of outdoor images in different light conditions, and they show high robustness. This project is part of the research taking place in Dalarna University / Sweden in the field of the ITS.

Black and white is always grey-the power of the police to conduct a strip search in Victoria

The performance of a strip search by a police officer is a serious interference with the liberty and dignity of an individual. However, it is considered by police to be an important part of their law enforcement armory and one that is increasingly necessary to utilise to assist in the investigation and prosecution of drug-related crimes. This article considers the troublesome issue of whether and in what circumstances the common law may extend to police the power to conduct a strip search. In addition, there is an examination of the statutes and regulations that purportedly give police in Victoria the power to strip search with particular attention given to ss 81 and 82 of the Drugs, Poisons and Controlled Substances Act 1981 (Vic).

Police perceptions of interviews involving children with intellectual disabilities: a qualitative inquiry

This study employed a qualitative method to explore the experiences of 20 police officers when interviewing children with intellectual disabilities. Three main themes were interpreted as representing challenges to the officers when interviewing special-needs children: police organizational culture, participants' perceptions of these children as interviewees, and prior information. Participants in this inquiry mentioned poor organizational priority within the police force for child abuse cases and children with intellectual disabilities, as well as inadequate support for interviewing skills development and maintenance. Participants also attempted to equalize these children by interviewing them in the same way as their mainstream peers. Finally, participants viewed interview preparation as influential in determining an interview's successful outcome, but recognized that preparedness could bias their interviewing techniques. Increased attention towards these issues will provide a basis for developing strategies to minimize such challenges and thus improve the quality of interviews with children with intellectual disabilities.

The trouble with woon: the selective answering of police questions and the right to pre-trial silence

The 1964 High Court decision in Woon v The Queen is commonly understood to permit the drawing of an inference of a ‘consciousness of guilt’ when a suspect selectively responds to police questions. It is the author’s contention that, in the light of the emphatic endorsement of the right to pre-trial silence by the High Court in 1993 in Petty v The Queen; Maiden v The Queen, Woon should now be regarded as bad law and should no longer be followed.

Child abuse investigation: an in depth analysis of how police officers perceive and cope with daily work challenges

Purpose: The purpose of the current study was two-fold: to explore police officers' perceptions of the daily challenges involved in child abuse investigation and how those challenges affect their ability to undertake child abuse investigations, and to explore how these challenges are managed on a daily basis. Design/methodology/approach: This study employed a qualitative research design. In-depth interviews were conducted with a diverse sample of 25 police officers working in child abuse units across three Australian states. Findings: Inductive thematic analysis revealed that heavy caseload and collaboration with other professional groups are two key sources of negative work stress frequently associated with child abuse investigation. Further, despite the provision of organisational strategies aimed at reducing work stress, the officers tended to rely predominantly on informal coping mechanisms.  Research limitations/implications: This study has raised many questions for further research aimed at developing interventions to assist police organisations in managing work stress. Originality/value: This paper provides an in-depth analysis of the key challenges associated with child abuse investigation and the coping mechanisms employed for overcoming these challenges from the unique perspective of police officers authorised to investigate child abuse.

Police officers' and legal professionals' perceptions regarding how children are, and should be, questioned about repeated abuse

This study explored the perceptions of police officers and legal professionals (i.e., prosecutors, defence lawyers and a judge) about (a) what particularisation is, (b) the type of information that is required for particularisation to occur, and (c) how particularisation is best achieved in cases of repeated child abuse. The professionals' perceptions (all experts in this area) were elicited via individual in-depth semi-structured interviews. While all participants acknowledged the importance of particularisation, the views of the police officers varied in several important ways to those of the other professionals. Overall, the police officers perceived that highly specific details (such as the location, date and time of the offence) are essential for particularisation to occur, and that maximising the number of separate offences and specific details about each offence increases the chance of successful prosecution. In contrast, the legal professionals perceived that the primacy goal of the police officers should be to elicit a free-narrative account of one or more offences. A high proportion of specific questions was perceived to negatively impact on the child's credibility by contaminating the evidence. The implications of these findings are discussed.

A simulation model for video traffic performance via ATM over TCP/IP

Although TCP has emerged as the standard in data communication, the introduction of ATM technology has raised numerous problems regarding the effectiveness of using TCP over A TM networks, especially when video traffic performance is considered. This paper presents a simulation model for transmission performance of video traffic via ATM over TCP/IP. The interactivity between TCP/IP and ATM, generation of MPEG traffic and evaluation of traffic performance are implemented in the model. The design and implementation details of the model are carefully described. The experiments conducted using the model and experimental results are briefly introduced, revealing the capability of our model in simulating network events and in evaluating potential solutions to performance issues.

MPEG Traffic Performance via TCP over ATM

A large volume of TCP/IP traffic is currently, and in the future will be, carried over ATM networks. A major part of the traffic, which is produced by multimedia sources, is encoded using the MPEG standard. For the performance analysis of transferring MPEG video sequence via TCP/IP over A TM networks, there is a need for appropriate simulation models. This paper describes one such simulation model that we have constructed. A sct of preliminary simulation experiments have been conducted with the mode to assess the impact of different network configurations on the MPEG traffic transmission performance. Our simulation model is able to simulate many of the potential performance issues regarding video traffic via TCPIIP and A TM and can be used to evaluate any potential solutions.

A performance comparison of three wireless multi hop ad-hoc network routing protocols when streaming MPEG4 traffic

Mobile ad-hoc networks are characterised by constant topology changes, the absence of fixed infrastructure and lack of any centralised control. Traditional routing algorithms prove to be inefficient in such a changing environment. Ad-hoc routing protocols such as dynamic source routing (DSR), ad-hoc on-demand distance vector routing (AODV) and destination-sequence distance vector (DSDV) have been proposed to solve the multi hop routing problem in ad-hoc networks. Performance studies of these routing protocols have assumed constant bit rate (CBR) traffic. Real-time multimedia traffic generated by video-on demand and teleconferencing services are mostly variable bit rate (VBR) traffic. Most of these multimedia traffic is encoded using the MPEG standard. (ISO moving picture expert group). When video traffic is transferred over MANETs a series of performance issues arise. In this paper we present a performance comparison of three ad-hoc routing protocols - DSR, AODV and DSDV when streaming MPEG4 traffic. Simulation studies show that DSDV performs better than AODV and DSR. However all three protocols fail to provide good performance in large, highly mobile network environments. Further study is required to improve the performance of these protocols in mobile ad-hoc networks offering VBR services.

Predictors of wellbeing experienced by Australian police officers

The aim of this study was to assess the ability of the Demand-Control-Support (DCS) model as well as the psychological contract model (PCM) to predict the wellbeing experienced by 2,566 Australian police officers. While the level of explained variance attributed to the PCM was substantially less than the DCS, measures of contract breach and organisational fairness still captured significant portions of intrinsic and extrinsic job satisfaction. Overall, the results of this study suggest that both the DCS and the PCM should figure prominently in strategies aimed at reducing or preventing police stress.